I have done both. The century I did two months after the marathon and it took me I think all of three weeks of riding a bike to do one. No way a centruy compares to a marathon. I think a century does stand up to a half marathon.

In my youth I used to run 15mile cross country and was good at it. My Club entered me in a marathon and I did it in under 3 hours- Did another couple that year, both under 3 hours but did not enjoy them.

Took up riding a lot later- and after a couple of years did a couple of metrics and then a 100 miler. Not really a problem but it was after a couple of years of High milage riding. Marathons or 100 mile rides- If you are fit enough- they are both about the same.

Now if you want a real challenge- 100 miles offroad- Done 10 of them and they are always hard.

Let's see. Years ago in Backpacker Magazine it was asked what is the maximum reasonable pace for packing (with full pack). Their answer was 5 MPH. That translates to a marathon of about 5 1/4 hours.

But would you really call this running a marathon? That is the big problem. There is a line between running and walking, not so in cycling.

Also a lot of marathons are rather flat. A hilly century is more difficult by any measure. But what is considered finishing a flat century is so easy it can be done by someone who has been of the bike for a long long time.

Let's look at the facts. The 2006 Tour de France was 3,657 kilometers which is about 2,257 miles over 23 days total which is about 100 miles a day and is ridden over largely mountainous terrain. How many marathons could a world class marathoner run over that terrain in 23 days?

If you compare apples to apples in terms of terrain, cycling is much easier. You do not have to support your body weight and you have a machine to help you.

That is why so many organizations are donating bicycles to underprivileged countries. So people can travel longer distances than by walking/running.

Also a lot of marathons are rather flat. A hilly century is more difficult by any measure. But what is considered finishing a flat century is so easy it can be done by someone who has been of the bike for a long long time.

+1

When it comes to cycling, terrain matters a lot more than it does in running. A hilly 50 miler can be far more difficult than a flat century. I'm not sure that's the case in running, except when the terrain is extremely hilly.

Ride a bike. It makes your legs stringy, and less tasty to our Kanamit friends.[SIGPIC][/SIGPIC]

When it comes to cycling, terrain matters a lot more than it does in running. A hilly 50 miler can be far more difficult than a flat century. I'm not sure that's the case in running, except when the terrain is extremely hilly.

Terrain always matters. If do our training on flat land for a 26.2 then do a hilly 26.2 things are not going to go as thought.

I've heard people say that a marathon is more comparable to a double century.

Considering my running ability, I think I would still find the double century easier.

I've done neither a double century nor amarathon, but I've done a couple centuries and probably run as far as 15 miles during training. The centuries seemed easier even than that, and I've been seriously into cycling for about 6 months, whereas I'd been running heavily for four years.

And cycling is just a lot more fun than running. I always feel god after a run (endorphins and such) but cycling I actualy have fun while excercising. For a distance runner, this is quite the novel concept.

I think if I woke up tomorrow morning and was told at gunpoint I had to choose between running a marathon in six hours or pedaling 200 miles on a bicycle in only eighteen hours, I'd still opt for the ride!

Weeks & CdCf, the comments from Lance Armstrong were what was in my mind when I made my comments. While confident that I would make the distance (not sure of the time ), it seems the "pounding" associated with a 26.2-mile run/jog/walk are what makes it particularly brutal. The knees and hips aren't getting quite as hammered while on the bike.

Walking isn't that "brutal". My normal walking speed is the same speed it would take to finish a marathon in six hours. I've never walked more than about 1/3 marathon though, but that's simply because I've never needed to.

a marathon is a RACE, right? a century is a ride, unless you are in a hundred mile road race.

Oh dear, no. At the level of most of us, they're both an 'event'. I have several bib numbers, from both running and cycling, where I have proudly described my tortured inabilities to the nearest second.

There is no coasting in running. Let's put it this way. I am overweight and I have no problem doing a century. There is no way I could do a marathon without losing a ton of weight. And even then I would need months of training to do it and not get hurt. Cycling is a lot easier.